1. Field of the Invention
This invention relates to a dial register apparatus of the kind typically used as an electricity watthour meter, and, more specifically, to a unidirectional register apparatus in which a mechanical register dial is driven in a single, upscale direction regardless of which direction, forward or reverse, a input gear assembly is driven.
2. Description of the Related Art
Dial registers of the type shown in FIG. 1 have been used to measure and record the consumption of utilities, such as water, gas, or electricity. The dial register assembly 100 illustrated in FIG. 1 includes a front plate 104, fastened to a back plate (not shown in FIG. 1) by means of spacer studs 102, with dial indicators 106 sweeping across (in a forward, upscale direction) dials 108 to record the consumption of, for example, kilowatt hours of electricity. Typically, the rightmost dial 108 (as viewed in FIG. 1) would display the "ones" value of kilowatt usage, the dial 108 to its immediate left would display the "tens" value of kilowatt usage, the dial 108 to its immediate left would display the "hundreds" value of kilowatt usage, and so on.
Among the various types of dial registers is the "unidirectional register," in which the dial indicators move only in a single, upscale direction regardless of which direction, forward or reverse, an input gear mechanism is driven. Unidirectional registers were originally developed to prevent attempts to defraud the utility companies by such actions which might cause the meters to register an improperly low rate of consumption. For example, in a bi-directional register, a consumer could simply rotate the input gear mechanism in a direction opposite that in which the input gear mechanism would normally rotate to register consumption. This will cause the bi-directional register to rotate in its reverse direction, causing the dial indicators to run downscale rather than upscale, thus decreasing the amount of power registered. To prevent such misuse of registers, and a consequent economic loss to utility companies, unidirectional registers were developed in which the register dial indicators always rotate in an upscale direction regardless of the forward or reverse direction of rotation of the input gear drive assembly.
An example of a unidirectional register is illustrated in FIGS. 2-4. As shown therein, the unidirectional register mechanism includes a reversing yoke 200 having two drive pinions 202 and 204 disposed thereon. The yoke 200 is coaxially aligned with a compound staff/gear 214, both of which rotate about an axle 222 (see FIG. 4). The compound staff/gear is engaged with an input gear 212, which receives a rotational input from an external source (not shown) which corresponds to the consumption of the utility being registered.
An idler gear (or reversing gear) 206 remains engaged at all times with an intermediate gear 208, which in turn engages a first recording gear 210. The unidirectional register mechanism is sandwiched between a front plate 218 and a rear plate 220 (see FIG. 4). The axle 222 is fitted through holes formed in the front plate 218 and the back plate 220.
FIG. 2 shows the input gear 212 being rotated in a forward (clockwise) direction. As a result, the compound staff/gear 214 rotates about the axle 222 in a reverse (counter-clockwise) direction. The friction present between the compound staff/gear 214 and the yoke 200 causes the yoke 200 to rotate about the axle 222 in the reverse direction until stopped by a stop member 216 which is used both to limit the travel of the yoke 200 and to limit the engagement of the pinion 204 with the intermediate gear 208. When the pinion 204 is in engagement with the intermediate gear 208, the intermediate gear 208 will be driven in the reverse direction, and the intermediate gear 208 will, in turn, drive the first recording gear 210 in the forward direction. The forward rotation of the first recording gear 210 causes the corresponding register dial indicator 106 (see FIG. 1) to move upscale across the dial face 108, thereby registering power consumption.
FIG. 3 shows the input gear 212 being driven in the reverse direction. As a result, the compound staff/gear 214 rotates in the forward direction. The friction present between the compound staff/gear 214 and the yoke 200 causes the yoke 200 also to rotate about the axle 222 in the forward direction until pinion 202 is brought into engagement with the idler gear 206, which, in turn, is caused to rotate in the forward direction. The idler gear 206, which is permanently engaged with the intermediate gear 208, drives the intermediate gear 208 in the reverse direction, thus driving the first recording gear 210 in the forward direction. As with the state of the register mechanism illustrated in FIG. 2, the forward rotation of the first recording gear 210 causes the corresponding register dial indicator 106 (see FIG. 1) to move upscale across the dial face 108, thereby registering power consumption.
In the above-described manner, the dial register is always driven upscale regardless of which direction, forward or reverse, the input gear 212 is driven.
However, in the state of the register mechanism illustrated in FIG. 2, the idler gear 206 is essentially superfluous, and may in fact cause inaccuracies in the recording of power consumption. That is, even though the intermediate gear 208 is being driven exclusively by the pinion 204 in the state shown in FIG. 2, the intermediate gear 208 remains engaged with the idler gear 206, thereby driving the idler gear 206 in the forward direction. In contrast, in the state of the mechanism illustrated in FIG. 3, in which the intermediate gear 208 is driven exclusively by the idler gear 206 (via pinion 202), the intermediate gear 208 is not in engagement with the unused pinion 204.
Because of the differences between these two states, when the register is in the state shown in FIG. 2 (i.e., input gear 212 is rotating in the forward direction), the intermediate gear 208 is subject to an unnecessary resistance equal to an amount of force required to rotate the idler gear 206 in the forward direction. In contrast, when the register is in the state shown in FIG. 3 (i.e., the input gear 212 is rotating in the reverse direction) the intermediate gear 208 is not subject to any unnecessary resistance because the unused drive gear (i.e., pinion 204) has been disengaged from the intermediate gear 208. As a result of the difference in resistive force, the register mechanism may record power consumption at different rates depending on which direction the input gear 212 is driven. In this manner, the reliability of the register mechanism is reduced because inaccuracies in the recording of power consumption may result. In addition, the configuration of the conventional unidirectional register illustrated in FIGS. 2-4 causes the overall device to be larger and more costly to manufacture.